Head Torque Without Rocker Box Removal (OIF Bikes)

onMay 3, 2012

The OIF is the problem here, the rocker box had to be modified to get the motor to fit the frame, so instead of the stud that passes right through the rocker box on the 1970 and earlier 650’s a bolt is threaded into a stud that finishes inside the rocker box. British Spares market a very useful kit that removes the need to take your rocker boxes off to torque down these studs. part no….. The 4 middle studs are replaced with studs that have the rocker box retaining bolts screw inside a hex (Allen key) socket. An allen key can be inserted through the bolt hole in the top of the rocker box to tighten the stud without removing the rocker box. Only problem I have with this is my torque wrench won’t fit between the head and the frame on my ‘oil in frame’ bike.

Nigel Sprocket recalls the OIF frame “Tea boy Ken Spall (no relation to Ken Spall TOMCC newsletter editor) wanders into the development room at Umberslade Hall – “ere mate, that motors too big to fit in that flash new frame” Umberslade Hall; “F**k off spindle dick, you can’t even make a decent cuppa, poke your nose in here again an we’ll ‘ave you”. Ken retreated to the tea room and quietly pissed in the tea urn. “That’ll teach them bleedy toffs.”

To get around this pop down to Shaddy’s place and borrow his short 3/8” Allen Key stub from his socket set. If he doesn’t live handy to you cut 1½” off the end of a 3/8” Allen Key. This ‘stub’ fits into the hex socket in the head stud. Place the ring end of a 3/8” spanner over the protruding end of the Allen Key and fit the torque wrench to the open end of the spanner, see photo.

My Torque wrench is ½” drive so I need to use a ½” to 3/8” reducing socket as well. The torque reading needs to be adjusted as follows; 15ft.lb multiplied by the length of the torque wrench divided by the length of torque wrench plus spanner. Measure the lengths from the centre of the socket drive and ring of spanner to the gauge on the torque wrench. For my 100mm long spanner and 330mm long wrench it’s 15ft.lbx330mm/430mm =12ft.lb. A little bit of stuffing around but it sure beats taking rocker boxes off every time. Don’t forget to reset tappets afterwards too.